ORIGINAL PAPER Titanium coated with high-performance nanocrystalline ruthenium oxide synthesized by the microwave-assisted sol–gel procedure Gavrilo Šekularac 1 & Milica Košević 1 & Ivana Drvenica 2 & Aleksandar Dekanski 1 & Vladimir Panić 1 & Branislav Nikolić 3 Received: 8 April 2016 /Revised: 13 July 2016 /Accepted: 21 July 2016 /Published online: 30 July 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract Ruthenium oxide coating on titanium was pre- pared by the sol–gel procedure from well-defined colloidal oxide dispersions synthesized by the microwave (MW)- assisted hydrothermal route under defined temperature and pressure heating conditions. The dispersions were characterized by dynamic light scattering (DLS) measure- ments and scanning electron microscopy (SEM). The elec- trochemical properties were analyzed as capacitive perfor- mances gained by cyclic voltammetry and electrochemical impedance spectroscopy and as the electrocatalytic activity for oxygen evolution from acid solution. The obtained dis- persions were polydisperse and contained regular particles and agglomerates of increasing surface energy and de- creasing particle size as the MW-assisted heating condi- tions were intensified. Owing to these features of the pre- cursor dispersions, the obtained coatings had considerably improved capacitive performances and good electrocata- lytic activity for oxygen evolution at high overpotentials. Keywords Activated titanium anodes . Dynamic light scattering . Pseudocapacitance . Noble metal oxides . Oxide sols Introduction Dimensionally stable anodes (DSA) are well-known electro- catalytic material with industrial applications in chlorine (CER) and oxygen evolution reactions (OER). Their activity originates from conductive noble metal oxides, especially RuO 2 and IrO 2 , applied as a coating on a titanium substrate [1–8], along with the titanium oxide that provides adhesion and the stability of the coating. The oxide coating on a DSA is usually prepared in situ from HCl or alcoholic solutions of the metal chlorides [1, 9–11] by pyrolysis [12–14], chemical va- por [15], laser [16], or induction heating [17] deposition tech- niques. The oxides can also be synthesized ex situ as hydro- thermal colloidal dispersions and then subjected to the men- tioned deposition techniques within sol–gel procedure for coating preparation [18–21]. Microwave (MW)-assisted procedures in recent years were proved to be powerful techniques for the synthesis of a variety of materials, especially metal oxides, through a hydrothermal route [22]. The MW-based synthesis approach offers fast and energy-efficient rapid heating methods with reliable control of the synthesis parameters. Heating by microwaves, contrary to traditional pyrolysis based on radiation energy transfer, in- volves the direct interaction of molecular species with the electromagnetic field. MWs directly affect the rotational ener- gy of molecules, which results in rapid and uniform 3D heating at the molecular level with extremely low- temperature gradients. These features of the MW-assisted ap- proach considerably shorten the synthesis time from several This article is dedicated to Professor György Inzelt, our dear friend, on the occasion of his 70th birthday, in recognition of his numerous scientific and educational contributions to contemporary electrochemistry. Electronic supplementary material The online version of this article (doi:10.1007/s10008-016-3343-z) contains supplementary material, which is available to authorized users. * Vladimir Panić panic@ihtm.bg.ac.rs 1 Institute of Chemistry, Technology and Metallurgy, Department of Electrochemistry, University of Belgrade, Belgrade, Serbia 2 Innovation Center of the Faculty of Technology and Metallurgy, Belgrade, Serbia 3 Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia J Solid State Electrochem (2016) 20:3115–3123 DOI 10.1007/s10008-016-3343-z